The Latin for weapons, or arms, was arma.
Our "art" and "article" came from the same root, art meaning something originally made by the use of the arms, hands and fingers.
The English "alarm" goes back directly to the Italian alle arme, and ultimately to the Latin ad arma so that "alarm" means "to arms, signifying that something has happened of possible danger.
A knock at the Lodge door is so named because it calls for alertness, lest the wrong man be permitted to enter.
- Source: 100 Words in Masonry